The present invention relates to a turbine housing, and to a method of making a turbine housing.
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
Internal combustion engines for motor vehicles are increasingly charged by turbochargers to reduce fuel consumption. However, fuel consumption is also impacted by the weight of the exhaust system so that turbochargers should have a lowest possible weight. On the other hand, turbochargers should also be robust enough to withstand significant mechanical and in particular high thermal stress during operation to which they are subjected. Still another consideration is the increasingly smaller installation space that is available in the engine compartment because of the increasing number of aggregates.
Various approaches have been suggested to find a compromise between lightweight construction of the turbochargers and desired service life. The service life of a turbocharger is particularly impacted by thermally induced stress. Therefore, the presence of thermal compensating elements has been proposed. This poses, however, a sealing problem. To address this problem, German Offenlegungsschrift DE 100 22 052 A1 proposes to decouple exhaust gas conducting components from supporting and sealing outer structures. While the internal system can hereby be tightly connected to the external system, thermal stress causes a deformation of the components so that there is a risk of collision of the internal system or rotor casing with the turbine rotor.
The internal system has to meet certain tightness requirements to ensure an efficient operation of the turbocharger. German Offenlegungsschrift DE 103 52 960 A1 describes the presence of a sliding seat to prevent thermal stress between a rotor casing and an overflow zone which conducts the exhaust to an exhaust flange. While elongation is compensated hereby, the presence of thermomechanical stress still undermines an economical production of the housing because of the necessarily required material properties and manufacturing tolerances necessary for a reliable operation.
It would therefore be desirable and advantageous to obviate prior art shortcomings and to realize maximum sealing effect of the internal system while allowing compensation of a temperature-caused elongation between the rotor casing and an exhaust pipe for the exhaust and use of thin-walled materials without the need for any welding works in the sensitive exhaust zone of the rotor casing.